Strength analysis of steel columns under influence of residual stresses and geometric imperfections

Resumo

Knowledge about the behavior of structures is of great importance for the correct design of a structural
project. Generally, it is desired to obtain lighter and slender structures, which, in addition to providing cost savings,
present a good performance in face of the requesting efforts. In addition, improvements in computational methods
for advanced analysis have favored the achievement of results closer to the structure’s real behavior. In this sense,
the objective of this article is to evaluate the influence of residual stresses and geometric imperfections on steel
columns subjected to bending around weak-axis, especially in columns with intermediate slenderness (40 ≤ l / r ≤
120). For this end, it is used the data obtained by a non-commercial software, called PPLANLEP program, which
is based on the Finite Element Method and is capable of considering the physical nonlinearity, modeled by the
distributed plasticity approach, and the geometric nonlinearity. In the analyses, residual self-balanced stresses due
to material manufacturing process are considered with different magnitudes and distributions on the flanges and
web for an I-type cross section. In addition, this factor is combined with different configurations of initial
geometric imperfections. Finally, the resistance curves of the columns are compared with the curves proposed by
the Brazilian standard ABNT NBR 8800: 2008 and European standard EN 1993-1-1: 2005. It is verified an
inadequacy in the use of the single buckling curve, adopted by the Brazilian standard, for flexural buckling about
minor axis. In addition, it is observed that the use of the buckling curve “c” proposed by the European standard is
more assertive for the design of columns subjected to bending around the weak-axis.